title: Solid-state NMR evidence for β-hairpin structure within MAX8 designer peptide nanofibers.
abstract: MAX8, a designer peptide known to undergo self-assembly following changes in temperature, pH, and ionic strength, has demonstrated usefulness for tissue engineering and drug delivery. It is hypothesized that the self-assembled MAX8 nanofiber structure consists of closed β-hairpins aligned into antiparallel β-sheets. Here, we report evidence from solid-state NMR spectroscopy that supports the presence of the hypothesized β-hairpin conformation within the nanofiber structure. Specifically, our (13)C-(13)C two-dimensional exchange data indicate spatial proximity between V3 and K17, and (13)C-(13)C dipolar coupling measurements reveal proximity between the V3 and V18 backbone carbonyls. Moreover, isotopic dilution of labeled MAX8 nanofibers did not result in a loss of the (13)C-(13)C dipolar couplings, showing that these couplings are primarily intramolecular. NMR spectra also indicate the existence of a minor conformation, which is discussed in terms of previously hypothesized nanofiber physical cross-linking and possible nanofiber polymorphism.
authors.affiliation: Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida, USA.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Leonard
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Cormier
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Pang
authors.forename: Maxwell I
authors.initials: MI
authors.lastname: Zimmerman
authors.forename: Huan-Xiang
authors.initials: HX
authors.lastname: Zhou
authors.forename: Anant K
authors.initials: AK
authors.lastname: Paravastu
mesh_terms: D000595:Amino Acid Sequence; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D057139:Nanofibers / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D010455:Peptides